fiber

1[uncountable]the part of food that helps to keep a person healthy by keeping the bowels working and moving other food quickly through the bodysynonymroughagedietary fiberDried fruits are especially high in fiber.a high-/low-fiber dietHe has been advised to increase his fiber intake.bran fiber

2[countable,uncountable]a material such as cloth or rope that is made from a mass of natural or artificial threadsnylon and other man-made fibers

3[countable]one of the many thin threads that form body tissue, such as muscle, and natural materials, such as wood and cottoncotton/wood/nerve/muscle fibers(literary)She loved him with every fiber of her being.see alsomoral fiber,optical fiber